Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, and 5-amino-2-methylphenol. A majority of the shades have been produced with dyes based on p-phenylenediamine.
For providing an orange coloration to hair 2-methyl-5-aminophenol has been extensively used in combination with p-aminophenol as a primary intermediate. However, the resulting orange color on hair undergoes significant changes on exposure to light or shampooing. U.S. Pat. No. 4,065,255 and EP patent publications EP 634165 A1 and EP 667143 A1 suggest the use of 2-methyl-5-N-hydroxyethylaminophenol, 2-methyl-5-alkylaminophenol and 2-methyl-5-aminophenol as couplers. Therefore, there is a need for new orange couplers for use in oxidative hair dyeing compositions and systems.